A 3-unsubstituted-5-amino-4-nitrosopyrazole compound can be utilized as a synthetic intermediate of a 4,5-diaminopyrazole compound which is a useful intermediate for a hair dye or antitumor agent (for example, Japanese Provisional Patent Publications No. 56981/1985, No. 273979/1987 and WO 94/0869).
As a process for preparing a 3-unsubstituted-5-amino-4-nitrosopyrazole compound, in Japanese Provisional Patent Publication No. 273979/1987, etc., there has been disclosed a method of obtaining 5-amino-1-(2-hydroxyethyl)-4-nitrosopyrazole hydrochloride by reacting 5-amino-1-(2-hydroxyethyl)-pyrazole with isoamyl nitrite in the presence of hydrogen chloride. However, in this method, there are problems that the reaction operations are complicated and a yield of the objective material is low.
Also, in J. Chem. Research Synopses, 10 (1992), there is described a method of producing 3-aryl or 3-heterocyclic substituted-4,5-diaminopyrazole compound, but with regard to a 3-position unsubstituted product, a process for preparing an oxime compound which is a starting material thereof is not disclosed, so that it cannot be synthesized. As a prior art with regard to a 3-hydrazono-2-hydroxyiminopropionitrile compound which is used for a process for preparing a 3-unsubstituted-5-amino-4-nitrosopyrazole compound of the present invention, a process for preparing 3-(dimethylhydrazono)-2-hydroxyiminopropionitrile from 3-(β-dimethylhydrazono-α-oxyiminoethyl)-1,2,4-oxadiazole has been described in Khim. Geterotsikl. Soedin., 7, 976 (1991) (English-language translated literature; Chem. Heterocycle Compd., 27 (7), 783 (1991)).
A 3-hydrazono-2-hydroxyiminopropionitrile compound of the present invention is a novel compound, and a process for preparing the same has never been known.
Also, 2-hydroxyimino-3-oxopropionitrile to be used for the process for preparing the 3-unsubstituted-5-amino-4-nitrosopyrazole compound of the present invention is a novel compound, and a process for preparing the same has never been conventionally known.
An object of the present invention is to solve the above-mentioned problems, and to provide a process for preparing a 3-unsubstituted-5-amino-4-nitrosopyrazole compound with a simply and easy method from starting materials which can be easily available with a high yield.
Another object of the present invention is to provide a novel 2-hydroxyimino-3-oxopropionitrile and 3-hydrazono-2-hydroxyiminopropionitrile compound to be used for the preparation of the above-mentioned 3-unsubstituted-5-amino-4-nitrosopyrazole compound and processes for preparing the same.